Exterior lighting is used to illuminate roadways, parking lots, yards, sidewalks, public meeting areas, signs, work sites, and buildings, to name a few examples. Traditionally, such lighting systems used high-intensity discharge (HID) lamps, often high pressure sodium (HPS) lamps. The move towards improved energy efficiency has brought to the forefront light emitting diode (LED) technology as an alternative to HID lighting in commercial and municipal applications. LED lighting has the potential to provide improved energy efficiency and improved light output in outdoor applications.
The Cobra Head type light fixture is perhaps the most commonly found style of roadway fixture. It would be advantageous to convert existing Cobra Head style HID lamps to LED light sources without having to discard the entire fixture assembly. There is therefore a need for an improved LED retrofit solution for outdoor applications that does not require replacement of the existing fixture.
With reference to FIG. 1, a typical roadway lighting fixture is depicted. The Cobra Head lighting fixture 1 comprises a housing 3 having a central longitudinal axis “L”. The housing 3 includes a center section 5 arranged about the center longitudinal axis “L” of the housing 3 and running substantially along one half the length of the longitudinal axis of the housing 3. The center section 5 defines a forward compartment enclosing an HID lamp 7 and a reflector 9. The compartment is accessed via a door (not shown) hinged to a bottom surface of the fixture to provide access to the compartment from below. Typically, the door includes an opening receiving a lens through which light generated by the HID lamp 7 exits the fixture 1. A rear section 11 of the housing 3 defines a rearward compartment housing a power supply 13 such as a ballast. The rear compartment also receives post 15. A second door (not shown) is provided to cover the power supply 13 and provide independent access thereto. Alternatively, a single door is provided which is hingedly connected to the fixture 1 and provides access to center section 5 and rearward section 11 when opened.
According to one available LED retrofit system a replacement LED light source can be installed as follows. First, the door of an existing roadway illuminaire is opened, the existing HID lamp, reflector and lens are removed and recycled. Optionally, the existing ballast and other electrical components can be similarly removed. An LED light engine is then installed into the opening in the door from which the lens was removed. A safety cable is installed between the LED light engine and a main body of the fixture. Power leads are attached between the LED light engine and the power leads of the light fixture. Thereafter, the fixture door is closed and latched to achieve final installation of the LED luminaire. Although functional, this design can suffer from thermal management issues.
The present disclosure is directed to an improved simple and economic LED module for replacement of an HID lamp in an outdoor fixture.